Method of producing seamless pipes utilizing a plug rolling procedure
AssigneeMannesmann Aktiengesellschaft
InventorKarl H. Hausler
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AssigneeMannesmann Aktiengesellschaft
InventorKarl H. Hausler
Estimating the term…
A method of producing seamless pipes by carrying out a plug rolling procedure includes expanding and stretching a hollow ingot into a bloom by carrying out at least two consecutive passes in a roll stand having a box-groove and by using a stationary plug supported by a rod. The bloom is pulled after each pass from the rod in a direction opposite the rolling direction. The bloom is turned after each pass by 90.degree. C. about a longitudinal axis thereof and the plug is exchanged after each pass. The method further includes the step of adjusting in one of the passes a wall thickness of the bloom in a wall portion of the bloom at the groove bottom by changing the roll distance in order to thin-stretching the wall portion such that the wall thickness of the finish-rolled bloom is uniform over the circumference thereof.
A method of producing seamless pipes by carrying out a plug rolling procedure in a rolling direction, the method comprising expanding and stretching a hollow ingot into a bloom by carrying out at least two consecutive passes in a single roll stand having rolls defining a box-groove and by using a stationary plug supported by a rod, pulling the bloom after each pass by means of a driving unit from the rod in a direction opposite the rolling direction, turning the bloom after each pass by 90.degree. C. about a longitudinal axis thereof before carrying out a subsequent pass, wherein the plug is exchanged after each pass, the groove having a bottom, the rolls being adjustable relative to each other to be spaced apart by a roll distance, the bloom having a wall and a circumference, further comprising the step of adjusting in a first pass a wall thickness of the bloom in a wall portion of the bloom at the groove bottom by changing and maintaing the roll distance in order to take into account thin-stretch of said wall portion in a subsequent pass such that the wall thickness of finish-rolled bloom is uniform over the circumference thereof thereby eliminating a need for any subsequent reeling installation processing of the finish-rolled bloom.
Dependencies are inferred from the claim text.